Dispersions and the production thereof



Patented Aug. 2, 1932 PATENT OFFICE RICHARD W. LEWIS, OF MONTCLAIR, JERSEY EMULsIoNs AND ma'rnnms, mmrnons AND rnocassas non. 'rnn rnnraaa'rron manner l io Drawing.

My present invention relates to dispersions and to processes and methods of preparing them. It relates particularly to dispersions such as those of bituminous material in water, to dispersing agents, to grinding and shredding agents for the disperse media, and to methods and processes of using said agents for preparing the dispersions, and is applicable in the arts generally.

In the dispersion of asphalt, for example, in water, materials such as clay are generally used which have the property of shredding or disintegrating the material to be dispersed when they are mechanically stirred together in the dispersing medium, in addition to the property ofcausing the one to be dispersed in the other. There are, however, certain agents which are efiective in holding the disperse medium in suspension in the dispersing medium when the former is presented in a sufliciently finely divided state but which by their nature or by reason of the proportions in which they are used are ineifective in themselves, to grind or shred the disperse medium 26 so that it may be dispersed.

I have discovered, however, that by saturating or impregnating a bed or slip of an inert finely divided grinding material with a dispersing agent of the last mentioned naso ture and mechanically stirring the material to be dispersed thereinto, the inert material tears or sheds the latter, and the dispersing agent then becomes effective to disperse it, and to maintain it in dispersion, the dispers in medium in such case being usually applied as the liquid is mixed with the grinding material to make a slip therewith. In the grinding action any tendency of the dispersing agent to serve as a grinder or, disintegrator of the dispersemedium is added to the efieotive tendency of the inert grinder. In some cases, however, though either the inert grinder or the dispersing agent alone may not have an efiective grinding tendency, I can select and use such ,ofthese as when taken and used together will have a resultant 7 effective grinding and dispersing action.

An example of an eifective grinding material incapable of maintaining a dispersion is '60 200-meshpowdcred silica, and of a dispers- Application med July 5, 1924-. Serial No. 724,291.

ing agent for use therewith is aluminum hydroxide; or a hydrosol. The impregnation of a grinding bed or slip such as of fine silica and water with such a mixture and the stirring thereinto of an asphalt, would result in the dispersion of the, asphalt in water.

It is then an object of my invention to provide a dispersing mixture or slip comprisin an inert finely divided grinding materia and a dispersing agent which by its nature or b reason of the proportions in which it is use is incapable in itself of shredding the material to be dispersedbut which is effective in holding the disperse material in dispersion when it is presented to it in a sufliciently o5 finely divided state.- i

It is further an object of my invention to provide methods and processes for grinding and disintegrating the material to be disparsed and producin a dispersion thereof 7 in the dis ersing me ium.

Other 0 jects of my invention will appear from the s ecification.

As grin in material I use finely divided material whic is harder than the-material to be dispersed, such as silica, slate dust, etc. For most purposes I employ such a powder which is also insoluble so as to avoid blooming thereof afterthe emulsion has been putin use and the dispersingv medium removed as in 30 the application of a bitumen emuls on in water in which the water dries out and the I bitumen hardens into a resistant covering.

Suitable dispersing agents I find to be for example tannic acid, soap, basic sulphates of 5 copper or of iron, aluminum h droxide, fer ric hydroxide, insoluble phosphate such for example as chemicals havin em irical formulas of R' P0 and It" PO, ferric or aluminum oxides and hydrates, hydrosols and hydro els of substances normally insoluble, etc. y the term hydrate, as for example aluminum hydrate, I intend any hydrate in- 1 clusive of the hydrosols, hydrogels, gelatinous precipitates, or normal hydroxides. 96

For dispersing media I use any substance in the liquid state which may be found desirable for such use, and for the dispersed material I use bituminous material, waxes, pitches, gums, -etc., such as stearin pitch, the 100 ample.

A mixture of finely divided material such as 900 lbs. of silica, 200 lbs.- of aluminum hydroxide, and water is agitated in a mechanical mixer while 9000 lbs. of a bitumen in the liquid or semi-liquid state is added. The proportions given are those used in shop practice to produce one useful dispersion, but other useful dispersions, of course, have been obtained by varying the relativeproportions to meet varying conditions of service of the material, and such dispersions are within the scope of my invention. The silica serves as a mechanical grinder and shredder for the bitumen while the aluminum hydroxide serves as an emulsifying agent with the result that the bitumen is dispersed in the Water.

The grinding base according to my invention is used in the emulsion as a filler when desired; or when desired it is separated centrifugally or settled out as by diluting the emulsion with sufiicient additional dispersing medium or other medium for that purpose and used over again. In some cases I make the dispersing process and the settling or separating process to .follow each other eyelically as parts or steps of a continuous process.

After once having started the shredding and grinding and dispersing of the material to be dispersed, I can in some cases continue the process with the addition of only the material to be dispersed, the dispersing medium, and the dispersing agent, because after active grinding has once been started the shredding tendency of the dispersion will be suflicient to continue the shredding. In other cases in such a continuous process it is necessary to add the grinding material in considerably lessened amounts only.

The dispersions may be qualified, depending upon the use to which they are to be put, by the addition of a material which is soluble or miscible in the dispersing medium, is volmore, all or certain of these materials will function better-as dispersin agents if one or more of the more active dispersing agents such as mentioned above are utilized in the process of production of the dispersion. In this way simple dispersions, or complex dispersions, asmay be desired, are produced at the will of the operator, and at the same time the desirable feature is available of predetermining the color of the finished dispersion by selecting as the dispersing agent or as one of the dispersing agents that oxide or other pigment giving the desired color.

The subject matter of invention disclosed in this application is disclosed and/or claimed in the following copending applications of Richard W. Lewis, to wit: Serial No. 33,304, filed May 27, 1925 (Patent No. 1,787,418); Serial No. 491,968, filed Oct. 29, 1930; and Serial No. 491,969, filed Oct. 29, I930.

Iclaim:

A dispersion of bitumen in water comprising a bitumen, water and a mixture for pre paring and maintaining the dispersiorn'comprising an element of the group consisting of.

silica and slate dust and an element of the group consisting of tannic acid and soap.

In testimony whereof I hereto afiix my signature.

. RICHARD W. LEWIS.

' atile, and which has little or no solvent effect on the dispersed material such as denatured alcohol in an asphalt-water dispersion for reducing the freezing point of the dispersion or dispersing medium to thereby permit the shipping and use of the dispersion in freezing weather. This material I add during or after the dispersing operation.

I have discovered that when the paint pigments of commerce, such as theiron oxides, chrome-green, and others, are utilized as dispersing agents that they produce stable dispersions and have the desirable property in such dispersions of irreversibility. Further- Patented Aug. 2, 1932 PATENT OFFICE RICHARD W. LEWIS, OF MONTCLAIR, NEW JERSEY DISPERSIONS THE PRODUCTION THEREOF I 0 Drawing.

My present invention relates to dispersions and to processes and methods of preparing them. It relates particularly to dispersions such as those of bituminous m aterial in water, to dispersing agents, to gr1nd ing and shredding agents for the disperse media, and to methods and processes of usin said agents for preparing the dispersions, an is applicable in the arts generally.

In the dispersion of asphalt, for example, in water, materials such as clay are generally used which have the property of shredding or disintegrating the material to be disrsed when they are mechanically stirred together in the dispersing medium, in addition to the property of causingthe one to be dispersed in the other. There are, however, certain agents which are efiective in holding the disperse medium in suspension in the dispersing medium when the former is presented in a sufliciently finely divided state but which by their nature or by reason of the proportions in which they are used are ineflective in themselves, to grind or shred the disperse medium so that it may be dispersed.

I have discovered, however, that by saturating or impregnating a bed or slip of an inert finely divided grinding material with a dispersing agent of the last mentioned nature and mechanically stirring the material to be dispersed thereinto, the inert material tears or'shreds-the latter, and the dispersing agent then becomes effective to disperse it,

and to maintain it in dispersion, the dispers ing medium in such case being usually applied as the liquid is mixed with the grinding material to make a slip therewith. In the grinding action any tendency of the dispersing agent to serve as a grinder or disintegrator of the disperse medium is added to the effective tendency of the inert grinder. In some cases, however, though either the inert grinder or the dispersing agent alone may not have an eflective grinding tendency, I can select and use such of these as when taken and used together will have a resultant efiective grinding and dispersing action.

An example of an efiective grinding material incapable .of maintaining a dispersion Applieation flled October 29, 1980. Serial No. 491,968.

is 200-mesh powdered silica, and of a dispersing agent for use therewith is aluminum hydroxide or a hydrosol. The impregnation of a grinding bed or slip such as of fine silica and water with such a mixture and the stirring thereinto of an asphalt, would result in the dispersion of the asphalt in water.

It is then an object of my invention to provide a dispersing mixture or slip comprisin an inert finely divided grinding material an a dispersing agent which by its nature or by reason of the proportions in which it is used is incapable in itself of shredding the material to be dispersed but which is effectivein holding the disperse material in dispersion when It is presented to it in a suificiently finely divided state.

It. is further an object of my invention to provide methods and processes for grinding and disintegrating the material to be dispersed and producing a dispersion thereof in the dis ersing medium.

Other objects of my invention will appear from the specification.

As grinding material I use finely divided material which is harder than the material to be dispersed, such as silica, slatedust barytes, marble dust andother forms of powdered calcite, fibrous talc, and-various artificial preparations such as the zinc oxide pigment of commerce and precipitated barium sulphate.

In fact, for the intended purpose there may be used most of the insoluble inorganic substances such, for example, as the class of substances knownas mineral fillers and which are readily obtainable commercially in suitable powdered form, provided only that the pulverization of the material has been carried far enough to permit of its forming a paste or mud when mixed with water but has not been carried far enough so that the individual particles are capable of acting as true emulsifying agents. From such a classification I exclude clay and other socalledcolloidal materials whose subdivision cannot be arrested at will. Such materials are excluded because of the fact that it is diflicult, if not impossible, to arrest the prog- 1 

